Not Applicable.
Not Applicable.
The invention relates generally to apparatus and methods used for removing material from inside a conduit. More particularly, the present invention relates to a system capable of monitoring and removing material built-up on the inside surface of, or disposed within, a conduit. Still more particularly, the present invention relates to a tubing conveyed tool used to clean and caliper a flowline, pipeline, or well tubing.
Undesirable materials that build-up, or otherwise collect, on the inside walls of conduits, such as well tubing, injection lines, pipelines, flowlines, boiler tubes, heat exchangers and water lines, are known to restrict or interfere with the desired movement of fluids and equipment through the conduits. As a result, in many cases, the conduit becomes useless, or inoperable for its intended purpose. Conduits used to transport hydrocarbons, or in other oilfield applications, are particularly susceptible to the deposit of undesirable, obstructive materials such as barium sulfate, strontium sulfate, calcium sulfate, calcium carbonate, iron sulfide, other scale precipitates (such as silicates, sulfates, sulfides, fluorides, carbonates), cement corrosion products, deteriorated conduit lining, and dehydrated material (such as drilling fluid).
Current techniques for cleaning conduits used in hydrocarbon or oilfield applications include tubing conveyed cleaning methods and pipeline pigging. Tubing conveyed cleaning methods typically involve running into a conduit a cleaning device disposed on a drill string, where the drill string may be standard drill pipe or coiled tubing. Tubing conveyed cleaning devices have included those that use mechanical means, such as cutting mills, bits, or reamers, and others that use pressurized jets, possibly containing abrasives, to clean deposits from the inside of a conduit.
Various tubing conveyed techniques for conduit cleaning involve the use of a mill or bit to remove obstructive material from conduits. The mill or bit is lowered into a conduit by a string of pipe or tubing and rotated to effectively cut any deposits from the inside of the conduit. In many applications, the mills or bits have a short useful life due to damage from contact between the mills and bits and commonly occurring hard, dense, obstructive materials. Therefore, mills or bits may have to be frequently removed from the conduit and replaced, consuming time and increasing expense. Further, rotation of the mill or bit may require additional component parts, such as a motor, bearings, and rotary seals, which are complex and costly to manufacture and operate and are also subject to failure.
These techniques are also largely ineffective at loosening and removing substantially all obstructive material without damaging the conduit. For example, the inside walls of conduits cleaned with mills or bits are highly subject to damage from contact by the mill or bit. Such contact commonly occurs when the obstructions in the conduit are unevenly dispersed, causing the mill or bit to jam or rub against, or cut into, the inside of the conduit. Further, reactive torque due to the rotation of the mill or bit can also cause it to contact the inside surface of the conduit and cause damage thereto. Such reactive torque may also accelerates deterioration to the tubing, such as coiled tubing, that carries the mill or bit.
Other tubing conveyed cleaning methods utilize jet nozzles that eject liquid or angular-shaped solid particles in a foam or liquid transport medium. These systems typically operate in low to moderate pressure ranges and have often proven ineffective at loosening or removing commonly encountered hard, tightly bonded obstructive materials, such as barium sulfate. Higher pressure systems have been known too damage the inside surface of metal conduits as a result of the angular solids cutting, scarring, and eroding the metal. These systems lack the ability to minimize or control the amount of damage that occurs to the metal conduit; therefore, their use is not entirely satisfactory for many applications.
Tubing conveyed systems also may not be preferred in systems having long horizontal runs because the weight of a steel tubing string may hinder the travel of the cleaning device. The weight of a steel tubing string may cause the string to rest on the inside of the tubing, creating a resistance to moving the tubing relative to the conduit. A steel tubing string may also not be flexible enough to be inserted into a conduit string having high angle bends or other tortuous pathways.
Pipeline pigging is also well known in the art and involves pumping a xe2x80x9cpigxe2x80x9d through a pipeline. A pig is inserted into a conduit and forms at least a partial seal against the conduit wall so that the pig can be pumped through the pipeline using pressurized fluid. The pig scrapes deposits from the wall as it moves through the conduit. Once the pig reaches the end of a section to be cleaned, it is either removed from the conduit or pumped back to the starting position. Typically, special equipment and installations must be provided to allow access to and from the conduit for the pig at one or more locations on the conduit, which increases capital equipment costs. Pipeline pigging may also be undesirable in applications having heavy deposits, which may prohibit the movement of a pig, or where running and retrieval of a pig is difficult, such as in deep water or harsh environments. Additionally, most prior art pigs are simply pumped through the conduit with no provisions for control or monitoring of the progress of the pig or the status of the conduit bore from the surface.
Thus, there remains a need for a system for loosening and removing undesirable materials built-up, or otherwise collected, on the inside surface of conduits, that allows for remote control and monitoring of the cleaning process. The preferred system is simple, cost-effective, and easy to manufacture and operate. Ideally, the system can utilize and interface with existing equipment. Especially well received would be a system that can quickly remove all, or substantially all, of the deposited materials. Further, it would be beneficial for the system to be capable of recirculating or reusing its cleaning mixture or the constituents of the cleaning mixture.
The preferred embodiments provide a system and apparatus for loosening and removing undesirable deposits from the inside surface of conduits while overcoming at least some of the shortcomings of the prior art. The present system does not cause substantial or undesirable damage to the conduit and is simple, cost-effective and easy to manufacture and operate. The present system can utilize and interface with existing equipment.
One preferred embodiment comprises a powered tool that can be passed through a pipe or other conduit for the removal of solids deposited on the inner wall thereof. The tool includes equipment for advancing the tool, measuring the amount of deposited solids, and removing the solids. The tool is mounted to a string of tubing that is preferably nearly neutrally buoyant, or substantially neutrally buoyant, flexible, and is adapted to allow hydraulic and electric communication between the tool and a control location.
One preferred embodiment of an apparatus for advancing the tool includes a selectively expandable body disposed on the outside of the tool and a valve that controls the flow of fluid through the tubing string. In an expanded position, the expandable body contacts the interior wall of the conduit, including any deposits located thereon, and creates at least a partial seal against the wall. In a first position, the valve directs fluid from the tubing string to a location upstream of the tool to create a pressure differential across the expandable body that forces the tool down the conduit. In a second position, the valve directs fluid from the tubing string to a location downstream of the sealing body to create a pressure differential to force the tool out of the conduit.
One preferred embodiment of an apparatus for measuring the amount of deposited solids is a sonic caliper device. A preferred sonic caliper is adapted to transmit sonic signals toward the wall of the conduit and receive the reflected signals. The sonic caliper is coupled to a processor that can determine the thickness of deposits on the inside of the conduit by analyzing the travel time of the sonic signals. It is preferred that the sonic caliper and processor combination be able to provide real-time solid deposit information to an operator or to a control system.
One preferred embodiment of an apparatus for removing the solids includes a plurality of nozzles that are used to direct a high pressure fluid at deposits on the inside of the conduit. The nozzles are preferably adjustable both in direction and magnitude of flow so that the nozzles can be efficiently used to remove deposits from the conduit. Fluid for the nozzles is preferably pumped through the tubing string from the surface and may contain abrasives or chemicals to aid in the removal of deposits.
Thus, the preferred embodiments provide a tubing conveyed system that monitors the inside diameter of a conduit and removes any deposits that may restrict the conduit. The preferred system is conveyed on a string of coiled tubing that is neutrally buoyant and provides for electrical and hydraulic connection between a tool and a control station. The preferred tool uses hydraulic power to remove deposits from the conduit as well as provide a motive force to control the location of the tool in the conduit.
Thus, the present invention comprises a combination of features and advantages that enable it to substantially advance the art associated with conduit and pipeline cleaning apparatus by providing a tubing conveyed system that can be monitored and controlled from the surface, but is capable of use in conduits with long horizontal runs, tight turns, and tortuous pathways. These and various other characteristics and advantages of the present invention will be readily apparent to those skilled in the art upon reading the following detailed description and referring to the accompanying drawings.